Metal packaging, comprising a box body onto which a peelable membrane is sealed

Abstract

The present invention relates to a metal package comprising a box body (2) onto which a peelable membrane (3) is sealed. The side wall (21) of the box body (2) terminates in a free edge (215) which includes a roll (216) oriented towards said outer face (212). The cup-shaped peelable membrane (3) includes a sealing wall (31) closing an access opening (A), and a peripheral band (32) sealed onto a receiving band (211a). The roll (216) has a height dimension (R) ranging from 0.5 to 1.6 mm; and a longitudinal dimension (C) between the free edge (321) of the peripheral band (32) and the longitudinal apex (2161) of the roll (216) is 0 to 1.5 mm. Figure for the abstract: 3

Description

Description of the invention: Metal packaging, comprising a body of box on which a peelable membrane is sealed Technical field of the invention The present invention relates to the technical field of metal packaging, comprising a can body on which a peelable membrane is sealed. State of the art Metal packaging is commonly used in the form of metal cans for packaging food. Such metal packaging can also be used for packaging other industrial products, such as paints. Some metal packaging includes a lid formed by a metal ring on which a peelable membrane is heat-sealed. Such a lid structure allows easy opening, directly by hand, without the need for a tool or accessory. However, using a metal ring is not optimal for various reasons, particularly material consumption. To overcome these disadvantages, there are metal packagings in which the peelable membrane is sealed directly onto the body of the can. But, here again, current “direct sealing” solutions are not entirely satisfactory. The cans in question are in fact higher so as to introduce and seal the peelable membrane, leading to increased material consumption at the can body level and a reduction in the useful volume of said metal packaging. Presentation of the invention In order to overcome the aforementioned drawback of the state of the art, the present invention provides a metal packaging, comprising a box body (also called "packaging body") on which a peelable membrane is sealed. The box body has a side wall, defining a longitudinal axis, which has an inner face and an outer face. The side wall is terminated by a free edge which delimits an access opening and which comprises a roll oriented towards said external face, which roll has a longitudinal apex. The inner face comprises, on the side of said free edge, a receiving strip on which said peelable membrane is intended to be sealed. The peelable, cup-shaped membrane includes: - a closing wall, closing said access opening, and - a peripheral strip, sealed on said receiving strip, comprising a free edge. And according to the invention, said roll has a height dimension ranging from 0.5 to 1.6 mm; the longitudinal dimension between said free edge of the peripheral strip and said longitudinal top of the roll is from 0 to 1.5 mm. According to the invention, such a structure offers various advantages, in particular an optimization of the consumption of metallic material and an increase in the useful volume. Other non-limiting and advantageous characteristics of the product according to the invention, taken individually or in all technically possible combinations, are the following: - said roll has a height dimension ranging from 0.7 to 1.5 mm; - the longitudinal dimension between said free edge of the peripheral strip and said longitudinal top of the roll is 0 to 0.8 mm; - the roll has a circular or oblong section; for an oblong section, the roll advantageously has a height dimension, parallel to the longitudinal axis, ranging from 0.5 to 1 mm, and a width dimension, perpendicular to the longitudinal axis, ranging from 1 to 2 mm, preferably from 1 to 1.5 mm; - the longitudinal dimension between the closure wall and the top of the roll is 2.5 to 5 mm, preferably 3 to 4.5 mm; - the peelable membrane comprises a tab which extends the peripheral strip; the tab is advantageously folded inwards, on the closure wall, or outwards, overlapping the roll; the tab advantageously has a width ranging from 15 to 38 mm, preferably from 15 to 30 mm, advantageously decreasing from the peripheral strip or of constant width, to avoid the risk of tearing; - the receiving strip has an angle equal to or greater than 0°, and less than 90°, relative to a longitudinal axis of said side wall, which angle is for example chosen from 0°, from 40 to 60°; - said peelable membrane is made of a preformable aluminum base material, having a thickness ranging from 50 to 90 μm, preferably 60 to 70 μm, advantageous for effective peeling; - said peelable membrane comprises an aluminum layer which is covered with at least one sealing layer; - the box body comprises either a crimped side wall and a bottom wall, to form a three-piece box, or a one-piece side wall and a bottom wall, for a two-piece box; preferably, the box body is made in two pieces, with a rolled / welded sidewall; - the side wall has a thickness of 0.13 to 0.24 mm for a three-piece steel box, 0.13 to 0.24 mm for a two-piece steel box, and 0.17 to 0.25 mm for a two-piece aluminum box. The present invention also relates to the method for manufacturing a metal packaging according to the invention, which comprises: - a step of supplying the box body and a step of supplying the peelable membrane, then - a direct sealing step, of the peelable membrane on the body of the box. According to other advantageous characteristics: -during the supply stage, the peelable membrane is shaped, for example by stamping, before being placed in the box body; - the sealing material is applied to the body of the box, where applicable including on the weld by applying the so-called heat-sealing re-seal varnish, - said direct sealing step is carried out by a sealing tool (possibly a heated sealing tool) chosen from a mandrel, a segment, a wheel; - the direct sealing step is carried out by a sealing tool chosen from a mandrel, which sealing tool comprises a front face, intended to cooperate with the sealing wall of the peelable membrane, and a peripheral face, intended to cooperate with the peripheral strip of the peelable membrane, which peripheral face is of generally frustoconical shape, diverging from the front face. Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Detailed description of the invention In addition, various other characteristics of the invention emerge from the appended description given with reference to the drawings which illustrate non-limiting embodiments of the invention and where: [Fig.1] is a general and sectional view of a metal packaging according to the invention; [Fig.2] is a partial and enlarged view of the metal packaging according to [Fig.1], illustrating in more detail the free edge of its side wall and the tab of the peelable membrane folded inwards; [Fig.3] is a partial and enlarged view of the metal packaging according to [Fig.2], illustrating in more detail the free edge of its side wall in the form of a circular roll; [Fig.4] is a partial and enlarged view of the metal packaging according to [Fig.2], illustrating in more detail the free edge of its oblong roll-shaped side wall; [Fig.5] is a partial and enlarged view of another metal packaging according to the invention, the receiving strip of which is inclined relative to the longitudinal axis; [Fig.6] is a partial and enlarged view of another metal packaging according to the invention, illustrating the tab of the peelable membrane folded outwards; [Fig.7] is a top view of an isolated peelable membrane; [Fig.8] is a schematic view of a box body and a peelable membrane, prior to a direct sealing step carried out by a mandrel-type sealing tool; [Fig.9] is a schematic and partial view of detail IX of [Fig.8], illustrating in particular the profile of the mandrel-type sealing tool; [Fig.10] is a schematic and partial view of detail X of [Fig.8], illustrating a preferred profile of the mandrel on the side of the tab of the peelable membrane; [Fig.11] is a schematic view of the can body and the peelable membrane according to [Fig.8], during the direct sealing step carried out by the mandrel-type sealing tool; [Fig.12] is a schematic and partial view of detail XII of [Fig.11], illustrating the cooperation between the mandrel, the box body and the peelable membrane; [Fig.13] is a schematic and partial view of detail XIII of [Fig.11], illustrating the cooperation between the mandrel, the box body and the peelable membrane (on the side of the peelable membrane tab). It should be noted that, in these figures, the structural and / or functional elements common to the different variants may have the same references. The present invention thus relates to a metal packaging 1, comprising a box body 2 on which a peelable membrane 3 is sealed. Such metal packaging 1 is, for example, intended to contain sterilized or pasteurized foods, dry products, liquids, non-food, non-sterilizable products. Box body The box body 2 comprises a side wall 21, defining a longitudinal axis 2'. The side wall 21, advantageously a ferrule or cylinder, has a cross-section (along a plane perpendicular to the longitudinal axis 2”) which is advantageously circular, oval or quadrilateral (square or rectangular). This side wall 21 has two opposite faces: - an inner face 211, intended to be oriented towards the storage volume V and to come into contact with the packaged product, and - an external face 212, opposite. The side wall 21 is terminated by a free edge 215 which delimits an access opening A. The free edge 215 comprises a roll 216 which is oriented towards the outer face 212 of the side wall 21. This 216 roll wraps around a 216' center. The roll 216 notably has a longitudinal peak 2161. By "longitudinal vertex 2161", we also advantageously mean the line of the roll 216 defined by a straight line which is tangent to said roll 216 and which extends perpendicularly to a generatrix 211a' of a receiving strip 211a on which the peelable membrane 3 is intended to be sealed. This longitudinal summit 2161 advantageously consists of a line whose shape corresponds to the section of the side wall 21, while having a section greater in dimension. According to the invention, the roll 216 has a height dimension R (advantageously measured parallel to the longitudinal axis 2') ranging from 0.5 to 1.6 mm. More preferably, the roll 216 has a height dimension R ranging from 0.7 to 1.5 mm. Generally speaking, the 216 roll advantageously has a section chosen from: - a circular section ([Fig.3]), or - an oblong section ([Fig.4]). For a circular section, the height dimension R corresponds to the diameter of the rolled section 216. For an oblong section, the 216 roll advantageously has the following dimensions: - a height dimension H, parallel to the longitudinal axis 2', ranging from 0.5 to 1 mm, and - a width dimension L, perpendicular to the longitudinal axis 2', ranging from 1 to 2 mm, preferably from 1 to 1.5 mm. Preferably, the major axis of the oblong roll 216 extends perpendicular to the longitudinal axis 2°. The inner face 211 comprises, on the side of the free edge 215, a receiving strip 21a on which the peelable membrane 3 is intended to be sealed. As mentioned previously, this reception band 211a is advantageously defined by a generator 211a°. This receiving strip 211a advantageously has an angle equal to or greater than 0°, and less than 90°, relative to the longitudinal axis 2° of said side wall 21. This receiving strip 21 has, for example, an angle ranging from 0° to 60° relative to the longitudinal axis 2° of said side wall 21. This angle is advantageously measured between the generator 21 1a' and the longitudinal axis 2' of said side wall 21. Generally, the angle of the receiving strip 21 la, relative to the longitudinal axis 2°, is for example chosen from: - 0°, so that the receiving strip 21a is parallel to the longitudinal axis 2” (figures 1 to 4 in particular), or - from 40° to 60° so that the receiving strip 21 diverges from the longitudinal axis 2°, advantageously of generally truncated cone shape ([Fig.5]). Preferably and generally, the receiving strip 21a has a width dimension ranging from 1.5 to 4 mm, preferably from 2.5 to 4 mm. Again generally, the box body 2 includes: - a side wall 21, and a bottom wall (not shown) attached by crimping, to form a three-piece box, Or - a side wall 21 and a bottom wall (not shown) in one piece, for a two-piece box. More preferably, in a conventional manner per se, the box body 2 is made in two pieces, with a rolled / welded side wall 21. In such a two-piece box, the side wall 21 advantageously comprises a second free edge 218, intended to be secured to the bottom wall by crimping. Still generally, the side wall 21 advantageously has a thickness chosen from: - 0.13 to 0.24 mm for a three-piece steel box, - 0.13 to 0.24 mm for a two-piece steel box, and - 0.17 to 0.25 mm for a two-piece aluminum box. Peelable membrane The peelable membrane 3 has a cup shape. It comprises: - a closing wall 31, closing the access opening A, and - a peripheral strip 32, sealed on the receiving strip 21 1a of the box body 3. The peripheral strip 32 has two edges: - a first edge 321, also called “free edge”, opposite the closure wall 31, and - a second edge 322, connected to the closure wall 31. According to the invention, a longitudinal dimension C (advantageously measured on the ge- neratrix 21 la' defined by the receiving strip 21 la) between the free edge 321 of the peripheral strip 32 and the longitudinal top 2161 of the roll 216 is from 0 to 1.5 mm ( [Fig.3]). More preferably, this longitudinal dimension C between the free edge 321 of the peripheral strip 32 and the longitudinal top 2161 of the roll 216 is from 0 to 0.8 mm. Furthermore, the longitudinal dimension F (advantageously measured on the generatrix 211a' defined by the receiving strip 211a) between the closure wall 31 (or at the level of the second edge 322 of the peripheral strip 32) and the longitudinal top 2161 of the roll 216 is advantageously 2.5 to 5 mm, preferably 3 to 4.5 mm ([Fig.3]). Likewise, the free edge 321 of the peripheral strip 32 advantageously extends in a transverse plane passing, at least approximately, through the center 216' of the roll 216. Generally, the peelable membrane 3 advantageously comprises a tab 35 which extends the peripheral strip 32, advantageously from the free edge 321. This tab 35 is useful for peeling the peelable membrane 3, when opening the metal packaging |. In this case, the tab 35 is advantageously folded: - inwards, on the closure wall 31 and extending in front of the peripheral strip 32 ([Fig.2] in particular), or - outwards, overlapping the roll 216 ([Fig.6]) and extending in front of the outer face 212 of the side wall 21. Generally, as shown in [Fig.7], the tongue 35 advantageously has a width dimension G ranging from 15 to 38 mm. The tab 35 may have a rectangular shape (with a constant width dimension G). More preferably, this tab 35 has a width decreasing from the peripheral strip 32 (more preferably from the free edge 321), to avoid the risk of tearing. In this case, the tab 35 advantageously comprises two parts: - an upstream part 351, comprising two concave lateral edges, and - a downstream part 352, in an arc of a circle. The width dimension of the upstream part 351 is greater than the width dimension of the downstream part 352. This shape is useful to avoid tearing when peeling and to fold down without making creases. Generally speaking, the peelable membrane 3 is advantageously made from a pre-formable aluminum base material, having a thickness ranging from 50 to 90 μm, preferably 60 to 70 um. Still generally, the peelable membrane 3 optionally comprises an aluminum layer which is covered with at least one sealing layer (for example polypropylene), advantageously two heat-sealing layers. Still generally, the peelable membrane 3 is advantageously chosen from among the classic peelable membranes 3 per se. This peelable membrane 3 has two opposite surfaces: - an outer surface, intended to be oriented towards the outside of the box body 2, - an inner surface, intended to be oriented towards the inside of the box body 2 and designed to be sealed on the receiving strip 21 la. Traditionally, the peelable membrane 3 comprises several layers: - a base layer, also called a “barrier layer”, upper, made of a strong and flexible material, for example aluminum, and - a lower sealing layer, adapted in particular to ensure sealing with the receiving strip 211a. Heat sealing material for the can body A heat-sealing material is advantageously distributed at least on the receiving strip 21a of the box body 2, including on the weld in the case of a three-piece box (application of a so-called heat-sealing re-champi varnish on the weld). “Heat sealing material” means a material capable of being activated to provide a sealing (or bonding) function when subjected to heating (e.g. local heating by conduction or induction). This heat-sealing material is for example chosen from polypropylene or polyethylene (for example in the form of a heat-sealing varnish which is advantageously made up of a polymer matrix and a polypropylene dispersion). Manufacturing method In practice, the method of manufacturing the metal packaging 1 according to the invention comprises: - a step of supplying the box body 2 and a step of supplying the peelable membrane 3, then - a step of “direct” sealing of the peelable membrane 3 on the box body 2. During the supply step, the peelable membrane 3 is advantageously shaped (a sealing wall 31 and a peripheral strip 32), for example by stamping, before being placed in the box body 2. The peelable membrane 3 is then in the form of a pre-stamped cup. This preliminary shaping is useful for avoiding creases at the peripheral strip 32. Furthermore, a sealing material is advantageously added to the box body 2, where appropriate including on the weld by application of the so-called heat-sealing re-seal varnish. For example, the sealing step is advantageously carried out by a heat sealing operation. Preferably, the sealing step is carried out by any suitable sealing tool 5, for example mandrels, segments, wheels. Preferably, the heat sealing operation consists of applying heating to the sealing tool 5 and / or the receiving strip 21 1a of the box body 2. The suitable sealing tools can be: - a direct heating emitter (for example, a heating sealing tool, for example, heating mandrels, heating segments, heating wheels), or - an indirect heating emitter (for example induction heating of the sealing tool and / or the receiving strip 21 1a of the box body 2). A sealing step using a sealing tool 5, in the form of a mandrel, is for example described below in connection with figures 8 to 13. In particular, figures 8 to 10 represent a box body 2 and a peelable membrane 3, prior to a direct sealing step carried out by the mandrel 5. And figures 11 to 13 illustrate the box body 2 and the peelable membrane 3, during the direct sealing step carried out by the mandrel 5. A mandrel 5 advantageously comprises two faces 51, 52 intended to cooperate with the peelable membrane 5, advantageously defined with respect to a longitudinal axis 5°: - a front face 51, intended to cooperate with the sealing wall 31 of the peelable membrane 3, and - a peripheral face 52, intended to cooperate with the peripheral strip 32 of the peelable membrane 3 (and with the receiving strip 211a of the box body 2). The front face 51 advantageously extends perpendicular to the longitudinal axis 5°. The peripheral face 52 is generally frustoconical in shape, diverging from the front face 51. The front edge 521 of the peripheral face 52, at the level of the front face 51, is advantageously chamfered, for example according to a curved section. Preferably, the diameter of this front edge 521 of the peripheral face 52 is less than the diameter of the receiving strip 211a of the box body 2. Preferably, the peripheral face 52 of the mandrel 5 defines a non-zero angle, diverging from the front face 51, relative to the receiving strip 211a of the body. box 2. More preferably, the peripheral face 52 of the mandrel 5 defines an angle ranging from 5° to 11°, diverging from the front face 51, relative to the receiving strip 211a of the box body 2. In this case, as illustrated in [Fig.9], the peripheral face 52 advantageously has an angle D ranging from 5° to 11° relative to the longitudinal axis 5', diverging from the front face 51. The angle D is still preferably from 7.5° to 9.5°. Preferably, advantageously before the sealing operation, the receiving strip 211a of the box body 2 advantageously has an angle equal to 0°, relative to said longitudinal axis 2' of the side wall 21. Furthermore, as illustrated in [Fig.9], the height E of the peripheral face 52 is at least equal to, or even greater than, the height of the peripheral strip 32 of the peelable membrane 3. Preferably, the height E of the peripheral face 52 is at least 3 mm. Preferably, the peripheral face 52 of the mandrel 5 comprises a reservation Re (opposite the front face 51), at the level of the tab 35 of the peelable membrane 3. The peripheral face 52 of the mandrel 5 is thus offset locally relative to the longitudinal top 2161 of the roll 216. A longitudinal dimension Rel (advantageously measured parallel to the longitudinal axis 5') between the reservation Re and the longitudinal top 2161 of the roll 216 is from 0 to 1.5 mm ([Fig.13]). This technical characteristic is particularly interesting so that the tab 35 does not adhere during the sealing operation with the roll 216, which will facilitate the subsequent opening / peeling operation. During the supply step (figures 8 to 10), the peelable membrane 3 is advantageously shaped and fitted onto the mandrel 5. In this context, the front face 51 of the mandrel 5 cooperates with the closure wall 31 of the peelable membrane 3; and the peripheral face 52 of the mandrel 5 cooperates with the peripheral strip 32 of the peelable membrane 3. Alternatively, the peelable membrane 3 is in a flat configuration, held against the front face 51 of the mandrel 5. And when the mandrel 5 is fitted into the box body 2, the peripheral strip 32 of the peelable membrane 5 is formed between the peripheral face 52 of the mandrel S and the receiving strip 211a of the box body 2, Generally, during the direct sealing step, the mandrel 5 and the box body 2 are maneuvered in a relative translational movement, in approach, so that the peripheral face 52 of the mandrel 5 fits within the receiving strip 211a of the box body 2 (figures 11 to 13). This nesting here generates an expanding deformation (also called radial deformation) of the receiving strip 211a of the box body 2, in a general truncated cone shape. This effort helps exert the pressure needed for sealing. This expanding deformation can also slightly promote subsequent peeling. The extension of the mandrel perimeter allows the creation of radial pressure or force to achieve the seal. The peripheral strip 32 of the peelable membrane 3 is then sandwiched between the peripheral face 52 of the mandrel 5 and the receiving strip 21a of the box body 2. The peripheral strip 32 of the peelable membrane 3 is then optimally sealed on the receiving strip 21a of the box body 2. In practice, the nesting depth Pe (of the peripheral face 52 of the mandrel 5 within the receiving strip 21a of the box body 2) is for example 3 to 4.5 mm. The nesting depth Pe (advantageously measured parallel to the longitudinal axis 5') is advantageously measured between the front face 51 of the mandrel 5 and the longitudinal top 2161 of the roll 216 ([Fig.12]). During this nesting, the radial deformation Ra (measured at the level of the longitudinal vertex 2161 of the roll 216 and perpendicular to the longitudinal axis 5”) is for example 0.2 to 0.8 mm, more preferably 0.35 to 0.55 mm ([Fig.12]). Furthermore, in the case of a three-piece box, the filling is advantageously carried out after the sealing of the peelable membrane 3 on the box body 2; this peelable membrane 3 then forms the lower base of the box body 2. A bottom wall (not shown) is then crimped at the level of the second free edge 218 of the side wall 21 which is located opposite the roll 216. Conversely, in the case of a two-piece box, the filling is advantageously carried out before the sealing of the peelable membrane 3 on the box body 2. In other words, the peelable membrane 3 is attached to the box body 2 after it has been filled. Advantage of the invention The metal packaging 1 according to the invention has the advantage of presenting an optimization of metal consumption, in particular due to the combination between: - the structure of the roll 216, and - the longitudinal dimension C between the free edge 321 of the peripheral strip 32 and the longitudinal top 2161 of the roll 216. This solution has the advantage of allowing an increased interior volume, with an equal quantity of metal. Another advantage of the invention is to provide a metal packaging which is dimensionally balanced (approximately the same diameter at the top and bottom). Of course, various other modifications may be made to the invention within the scope of the appended claims.

Claims

Claims

1. Metal packaging, comprising a box body (2) on which a peelable membrane (3) is sealed, which box body (2) comprises a side wall (21), defining a longitudinal axis (2') which has an inner face (211) and a face exterior (212), which side wall (21) is terminated by a free edge (215) which delimits an access opening (À) and which includes a roll (216) oriented towards said outer face (212), which rolled (216) has a longitudinal summit (2161), which inner face (211) comprises, on the side of said free edge (215), a receiving strip (211a) on which said membrane peelable (3) is intended to be sealed, which peelable membrane (3), in the shape of a cup, comprises: - a closing wall (31), closing said access opening (A), and - a peripheral strip (32), sealed on said receiving strip (211a), comprising a free edge (321), characterized in that said roll (216) has a height dimension (R) ranging from 0.5 to 1.6 mm, and in that a longitudinal dimension (C) between said free edge (321) of the peripheral strip (32) and said longitudinal top (2161) of the roll (216) is 0 to 1.5 mm.

2. Metal packaging, according to claim 1, characterized in that said roll (216) has a height dimension (R) ranging from 0.7 to 1.5 mm.

3. Metal packaging, according to any one of claims 1 or 2, characterized in that the longitudinal dimension (C) between said free edge (321) of the peripheral strip (32) and said longitudinal vertex (2161) of the rolled (216) is 0 to 0.8 mm.

4. Metal packaging, according to any one of claims 1 to 3, characterized in that the roll (216) has a circular section or oblong.

5. Metal packaging, according to claim 4, characterized in that, for an oblong section, the roll (216) presents: - a height dimension (H), parallel to the longitudinal axis (2°), going from 0.5 to 1 mm, and - a width dimension (L), perpendicular to the longitudinal axis (2°), going from | to 2mm.

6. Metal packaging, according to any one of claims 1 to 5, characterized in that the longitudinal dimension (F) between the closure wall (31) and the longitudinal top (2161) of the roll (216) is 2.5 to 5 mm.

7. Metal packaging, according to any one of claims 1 to 6, characterized in that the peelable membrane (3) comprises a tab (35) which extends the peripheral strip (32).

8. Metal packaging, according to claim 7, characterized in that the tab (35) is folded: - inwards, on the closure wall (31), or - outwards, overlapping the roll (216).

9. Metal packaging, according to any one of claims 7 or 8, characterized in that the tongue (35) has a width ranging from 15 to 38 mm, advantageously decreasing or of constant width from the peripheral strip (32).

10. Metal packaging, according to any one of claims 1 to 9, characterized in that the receiving strip (21 la) has an equal angle or greater than 0°, and less than 90°, relative to said longitudinal axis 2') of said side wall (21), which angle is for example chosen from 0° or from 40 to 60°.

11. | Method for manufacturing a metal packaging according to one of any of claims | to 10, characterized in that it comprises: - a step of supplying the box body (2) and a step of supplying of the peelable membrane (3), then - a direct sealing step of the peelable membrane (3) on the body of box (2).

12. Method according to claim 11, characterized in that, during step of supply, the peelable membrane (3) is shaped, for example by stamping, before its placement in the box body (2).

13. | Method according to any one of claims 11 or 12, characterized in that a sealing material is applied to the box body (2), the case where applicable including on welding by application of the so-called varnish heat-sealing re-champi.

14. Method according to any one of claims 11 to 13, characterized in that said direct sealing step is carried out by a tool of sealing (5) chosen from a mandrel, a segment, a wheel.

15. Method according to claim 14, characterized in that said step of direct sealing is carried out by a mandrel (5) comprising: - a front face (51), intended to cooperate with the sealing wall (31) of the peelable membrane (3), and - a peripheral face (52), intended to cooperate with the peripheral strip (32) of the peelable membrane (3), which peripheral face (52) is of generally truncated cone shape, diverging from said front face (51).